Art galleries throughout Britain face being “inundated” with performance and other off-beat artists demanding equal rights to exhibition space after a Unitarian performance artist took the Tate Galleries to court today.

Anthony Padgett, 38, told an employment appeal tribunal in London that he was the victim of “institutional discrimination” on religious grounds after Tate Modern rejected his proposal for a piece of Unitarian performance art at the gallery in 2005.

His propsal, submitted in 2005, was to put on a performance around a reconstruction of a memorial to Sir Henry Tate, the Unitarian Christian who founded The Tate.

“That proposal was rejected and I claim it was rejected because of institutional discrimination against art of a positive religious content,” Mr Padgett told The Times.

The tribunal was was examining whether performance art is covered by the Employment Equality Regulations (Religion or Belief) 2003, which outlaw discrimination against employees and those who “personally do work” on religious grounds.

Unitarianism is a non-Trinitarian form of Christianity that is known primarily for being inclusive of many belief systems and lifestyles. Famous members include World Wide Web founder Tim Berners-Lee.

Performance art began in the 1960s as a form of protest art.

Two examples of performance artists are Yoko Ono and the controversial Gilbert and George, whose recent exhibition in the Tate included works such as Shitty Naked Human World, which included a depiction of the Christian Cross in human excrement.

The tribunal reserved its decision. The issue of discrimination will be addressed in the next hearing if today’s tribunal decides it has jurisdiction.

Mr Padgett said afterwards: “My point was that the whole point of discrimination legislation is to ensure that businesses act fairly and if there was a regulation in selection procedures, and transparency, there would not be that discrimination.”

If commissioned, he would in his piece have examined the relationship between art, religion, democracy, terrorism and globalisation. “I would have been doing that dressed in a suit adorned with religious symbols in the persona of the ‘Business Messiah’. The concept of the Business Messiah is about the relationship between religion, consumerism and capitalism and the unfettered creative consumption of religious beliefs.”

A spokesman for Tate Galleries said: “For legal reasons we are not allowed to discuss the case in detail. Anthony Padgett, not an employee of Tate, put in an unsolicited proposal for work of art and claims our rejection of the proposal discriminated against him on religious grounds. Tate does not discriminate against artists or employees for their religious belief or ethnic background. Tate supports artists and their freedom of expression when making art works.”